Effect of Limonene and a Cinnamaldehyde–Carvacrol Blend on the Fermentation, Nutritional Quality, and Aerobic Stability of Corn Silage

This study evaluated the effects of essential oils, such as limonene (LIM) and a cinnamaldehyde–carvacrol blend (CCB), on the fermentation, chemical composition, in vitro digestibility, and aerobic stability of corn silage stored for 150 and 200 days. Treatments included a control, CCB (100 and 200 mg/kg DM), and LIM (100 and 200 mg/kg DM). Essential oils improved fermentation by increasing lactic acid (up to 7.46% of DM) and reducing proteolysis (NH3-N: 0.46–0.59% of total N). Limonene, particularly at 100 mg/kg DM, enhanced the lactic:acetic acid ratio (up to 3.07), better preserved non-fiber carbohydrates (≈32.7%), and increased in vitro DM digestibility (up to 81.5%) compared to the control (≈76.0%). The CCB treatment raised acetic acid concentrations (up to 3.04% of DM). Extending storage to 200 days reduced DM recovery (≈84.0%) versus 150 days (92.5%). Treated silages showed greater aerobic stability, with a lower pH increase after 72 h of air exposure, most notably in the LIM 200 treatment (pH 4.10) compared to the control (pH 5.40). Essential oils, particularly limonene, effectively improve the fermentative quality, nutritional value, and aerobic stability of corn silage under prolonged storage.